Square-bottom bag of weldable material



Feb. 20, 1968 F. F. BROCKMULLER SQUARE-BOTTOM BAG OF WELDABLE MATERIALOriginal Filed July 16, 1965 2 Sheets-Sheet 1 In ven tor: FriedrichFranz BROCKMULLER his Afforney 2 Sheets-Sheet Feb. 20, 1968 F. F.BROCKMULLER SQUARE-BOTTOM BAG OF WELDABLE MATERIAL Origihal Filed July16, 1963 In venlor: Friedrich Franz BROCKMULLER 6 Ma his Afforney UnitedStates Patent 3,369,731 SQUARE-BOTTOM BAG 0F WELDABLE MATERIAL FriedrichFranz Broclrmuller, Lengerich, Westphalia, Germany, assignor toWindmolier & Holscher, Lengerich, Westphalia, Germany, a firm Originalapplication July 16, 1963, Ser. No. 295,440, now Patent No. 3,272,093,dated Sept. 13, 1966. Divided and this application May 20, 1966, Ser.No. 578,919 Claims priority, application Germany, July 21, 1962, W32,643 2 Claims. (Cl. 229-625) ABSTRACT OF THE DISCLOSURE A flat-bottomplastic bag, consisting of a hose section, formed at least at one end bymeans of corner folds so that a hexagon is formed, and comprising atleast one base sheet, secured to the edge of the hose at the bottom byknown means, i.e. welding, glueing, etc., in the form of two pairs ofsealed seams, which are perpendicular with respect to each other, andone pair of which is parallel to the longitudinal axis of the hosesection; the sealed seams of the two pairs of sealed seams crossing eachother. This application is a division of application Serial No. 295,440,filed July 16, 1963, now U.S. Patent No. 3,272, 093.

The invention relates to a square-bottom bag of a plastic material.

The manufacture of simple and cheap wrappings is essential for theeconomical use of plastic materials, preferably for throw-awaywrappings, and used particularly for materials sensitive to moisture,such as, for example, artificial fertilizers, plastics granulates andcement.

There are already known plastic valve bags, made of a hose section whichis welded at both ends and has a filler valve near one end. These bags,known to the trade as cushion bags, have the shape of a cushion whenfilled and cannot be stored reliably and in a space-saving manner.

The advantage of a good shape in the filled condition is offered by theso-called flat-bottom bags. Such bags made of plastic materials arealready known, but, owing to their uneconomical manufacture, they havenot been widely adopted. An essential reason is the considerablematerial expenditure connected with the manufacture of the bottom.

The present invention has therefore the object of providing afiat-bottom bag of plastic material which can be manufactured at minimummaterial expenditure and by means of machines.

This object is realized by a fiat-bottom bag, consisting of a hosesection formed at one end by means of corner folds so that a hexagon isformed, and comprising at least one base sheet secured to the edge ofthe hose at the bottom by known means i.e. welding, glueing, etc.

According to the method for manufacturing the new flat-bottom bag, asection of hose is flattened at the end by means of corner folds and abase sheet is applied to this bottom end, followed by securing this basesheet first to the edge of the corner folds covered thereby, and then tothe remaining edge of the hose, also covered by this base sheet.

For manufacturing a valve bag it is necessary also to expand and flattenthe other end of the hose section and to secure together two base sheetsof equal or different lengths, and offset one relative to the other, andapplied to the end where the valve bottom is to be formed, and finallysecured to the edge of the hose section.

In a preferred embodiment of this fiat-bottom bag, each corner fold hasa free end, formed by a cut in the edge of the hose section andconnected with the base sec- 3,369,731 Patented Feb. 20, I968 tion by asealed seam, and the sealed seams connecting the edge portions of thebottom end located perpendicularly to the direction of the hose crossthe sealed seams of the corner folds.

The invention will be further described, by way of example, withreference to the accompanying drawings, in which:

FIG. 1 shows a section of hose used according to the invention;

FIGS. 2 to 4 and 7 to 9 show the individual manufacturing stages of afirst embodiment of a flat-bottom valve FIGS. 5 and 6 are cross-sectionsalong the lines VV and VIVI in FIG. 4, respectively;

FIGS. 10 and 11 are cross-sections along the lines XX and XIXI,respectively, in FIG. 9;

FIG. 12 shows the valve bottom end of a flat-bottom valve bag accordingto a second embodiment in the stage corresponding to that shown in FIG.7;

FIG. 13 is a cross-section along the line XIIIXIII in FIG. 12;

FIG. 14 shows the finished valve bottom end; according to the secondembodiment of this invention;

FIG. 15 is a cross-section along the line XVXV in FIG. 14;

The new method of manufacturing a fiat-bottom valve bag will now bedescribed with reference to FIGURES 1 to 11.

A plastic hose section 1 is provided at both edges 2, 3 with short cuts4 in both layers of the flattened hose (FIG. 1). Then the ends of thehose section 1 are opened out (FIG. 2) and flattened down (FIG. 3),forming corner folds 5, 6, 7, 8 which have an extension 9, formed by therecesses or cuts 4. Then a base sheet 10 is applied to the bottom endhaving the corner folds 5 and 6 (FIGS. 4 and .5), whilst the bottom endwith the corner folds 7 and 8 is provided with two bottom sheets 13, 14of equal length, but offset one to the other, and connected by spotwelds or by spot glueing 11, 12 (FIGS. 4 and 6). Next the base sheets10, 13, 14 are connected with the extensions 9 of the corner folds bywelding, glueing, etc. (seams 15 in FIG. 7). Finally, the parts of theedges 2, 3 perpendicular to the direction of the hose are secured to thebase sheet 10 or the base sheets 13, 14 (seams 16 in FIG. 8). Thearrangement of the sealed seams is here such that the seams 15 cross theseams 16. After cutting off the portions of the longitudinal side edgesof the bottom which project over the seams 16, the flat-bottom valve bagis finished (FIG. 9). As may be seen from FIG. 11m the two bottom sheets13, 14 form a valve. The two spot connections 11, 12 are spaced one fromthe other, forming a valve duct between them.

FIGURES 12 to 15 show a second embodiment of a valve bottom end of afiat-bottom valve bag.

The open end of a flat-bottom valve bag, having the corner folds 20, 21,is provided with two base sheets 22, 23, but in this embodiment thesesheets are of different lengths. Also here, these two sheets areconnected by spot connections 11, 12. The lengths of these two sheetsare such that the desired offset is obtained at one end, whilst theother ends are flush. In order to secure the lower base sheet 23 to thecorner fold 21, the base sheet 22 is applied to the bottom end in afolded condition, forming a rim 24 (FIGS. 12 and 13). In this condition,the base sheets are connected to the corner folds. Then the edge 24 isfolded back and the two base sheets 22, 23 are secured to the edgeportions of the hose end; normal to the direction of the hose, as in thefirst embodiment (FIGS. 14 and 15). Also here, the portions of the longbottom edges projecting over the longitudinal bottom seams are finallycut off.

By extending the base sheets 22, 23to the right in FIG. 15and thecorresponding extension of the longitudinal bottom seams, it is possibleto form a protruding valve hose which may be sealed after the filling ofthe bag.

The long bottom seams, running normal to the direction of the hose, andthe cutting off of the protruding portions from the bottom edges may beeffected by any suitable, known means, which are not shown and need notbe described.

It is of course to be understood that what has been described above isapplicable not only to square-botto1n welded or glued plastic valvebags, but also to square bottom bags the individual parts of which aresecured to each other by other means other than welding or glueing.

What is claimed is:

1. A flat-bottom plastic bag, which forms a flattened hose section whenempty, and ha a parallelepidal shape when filled, comprising an endformed by a pair of end flaps respectively integral with and extendingfrom opposite sides of said hose section, said pair of end flaps formingrespectively a pair of opposite triangular corner folds, said end havingan overall hexagonal shape, at least one base sheet secured to said endby means of a first pair of scaled seams securing said base sheet tosaid end flaps, said first pair of scaled seams being transverse to thelongitudinal axis of said flattened hose section, and by'means of asecond pair of sealed seams securing said base sheet to said pair ofopposite corner folds, said second pair of sealed seams being parallelto said longitudinal axis of said flattened hose section, the seams ofsaid first pair of sealed seams extending over the seams of said secondpair of sealed seams and, respectively, ending beyond the seams of saidsecond pair of sealed seams at a point within the short edges of saidtriangular corner folds.

2. The flat-bottom plastic bag as set forth in claim 1, wherein theopposite end from said end of said hose section is identical to said endexcept that two base sheets are secured to said opposite end, said twobase sheets being secured to each other in an offset arrangement anddefining a valve passage therebetween.

References Cited UNITED STATES PATENTS DAVID M. BOCKENEK, PrimaryExaminer.

